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چکیده
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A study was undertaken to determine the effects of supplemental multicarbohydrase (MC) and butyrate glycerides (BG) on productive performance, nutritional, and physiological responses in laying hens fed corn- or wheat-based diets during a 12-week production period (from 50–62 wk of age). The experiment consisted of a 2 × 2 × 2 factorial arrangement of the treatments with 2 different basal diets (corn- or wheat-based diets), 2 concentrations of MC (0 or 200 mg/kg of diet), and 2 concentrations of BG (0 or 2 g/kg of diet). Each treatment had 6 replicates with 8 hens each. The interactions among diet, MC, and BG were observed for egg production (P = 0.048), feed conversion ratio (P = 0.005), and ileal Escherichia coli count (P = 0.043), indicating that the effects of MC and BG on these responses were more marked when wheat-based diet was fed. A diet × MC interaction (P < 0.05) was also detected for egg mass, eggshell breaking strength, jejunal viscosity, and digestibility coefficients of fat and ash. Replacing 100% of the corn with wheat in the diets of laying hens negatively affected (P < 0.05) yolk color index, eggshell thickness, digesta viscosity, jejunal morphology, and populations of ileal microbiota. By contrast, MC supplementation increased (P < 0.05) eggshell thickness, digestibility coefficients of energy and crude protein, and populations of Lactobacillus and Bifidobacterium spp. in the ileum. Inclusion of BG also resulted in greater (P < 0.05) jejunal villus height and villus surface area, and digestibility coefficients of protein and ash, but lower (P < 0.05) populations of total bacteria, Salmonella and E. coli in the ileum. Results indicate that while the complete substitution of corn by wheat has a detrimental effect on productive performance and gut health, the combination of MC and BG may have synergistic effects on improving productive performance and intestinal microbiota in laying hens fed the wheat-based diets during the late laying period.
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